CASPER, Wyo. — In a newly published paper seeking to assess the broad economic impacts that specific invasive weed species have on Wyoming agriculture, UW researchers found that one weed in particular, cheatgrass, could cause upwards of $110 million in damage yearly if left unchecked. Its greatest footholds happen to be in Natrona and Campbell counties.

The paper, titled “Current & Potential Economic Impacts of 10 Invasive Weed Species in Wyoming,” can be read in its entirety for free here. Alongside cheatgrass, the report’s authors investigated the economic impacts of hoary cress, leafy spurge, medusahead, palmer amaranth, perennial pepperweed, Russian knapweed, Russian Olive, ventenata and yellow starthistle.

However, cheatgrass stands out as the most pervasive and costliest of all the unwelcome flora Wyoming hosts. Boasting 2 million acres affected with it each, Natrona County and Campbell County could expect to feel some of the greatest economic effects if the plant were left free to spread.

Cheatgrass growing in ground with seeds (Shutterstock)

Both counties are also host to many of the other invasive species spreading across the state. Notably, Campbell County is home to the second largest population of ventenata anywhere in the state, just behind Sheridan County. Roughly 80,000 acres of Campbell County land has ventenata growing on it.

Despite having nearly the same total acreage with cheatgrass present, Campbell County is significantly more impacted by the weed than anywhere in the state, with 1 million of those 2 million acres significantly impacted. In Natrona County, only about half a million acres are truly impacted, according to the report’s authors, though it has about 1 million more acres more suitable to the weed than Campbell County does.

Presence in total acreage of cheatgrass by county across Wyoming, as estimated by Wyoming Weed and Pest (Screenshot)

What difference does the presence of one type of grass really have over the other? The report estimates that cheatgrass already costs the state’s agriculture industry millions yearly and could cost even more if not properly managed.

“Cheatgrass has the highest loss estimates statewide with $32 million in direct loss on observed acres and $110 million in potential loss from infestation on suitable habitat,” the report’s authors said. “Cheatgrass infestation resulted in a 13% reduction in agricultural value across Wyoming in 2021. If cheatgrass were to spread to all potential habitat in the state this loss would grow to a 43% reduction from estimated agricultural value without cheatgrass.”

Ventenata alone cost $1 million the same year where it was present.

The report also identified the number of job years potentially supported from household spending in the Wyoming economy if direct agricultural value loss from weed infestation were avoided. For cheatgrass in the entire state of Wyoming, the report estimates that almost 150 jobs don’t exist because of the plant. In Campbell County, landowners are missing out on $4.4 million in lost annual cash rent.

This is because the weed is highly competitive over other plant species, less digestible than other plant matter to livestock and much more susceptible to spreading wildfires than other grasses. Since it grows in wild rangeland where livestock feed and it is typically very dry, this weed also poses a lot of danger to property.

Identifying cheatgrass

According to Natrona County Weed and Pest, cheatgrass — a noxious weed, as declared by the county — is a winter annual plant that grows between 4 and 30 inches tall. The plant is covered in soft, dense hairs and droops at the head, where the seeds are distributed.

Natrona County Weed and Pest also gave a short description on how it is so effective at getting around. “Seeds stick in clothing, shoes, and fur,” Weed and Pest said. “Mature plants are not palatable to livestock. It invades pastures, prairies, and rangeland areas.”

Use of chemical pesticides is an option for dealing with the weed and is typically done in the late months of the year. Afterward, distributing noninvasive seeds can boost competition and limit cheatgrass growth.

It is advised that landowners contact their respective county’s weed and pest center for recommendations as to how to diagnose and properly deal with invasive cheatgrass presence. Natrona County Weed and Pest’s website can be found here, while Campbell County Weed and Pest’s website can be accessed here.

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